Vehicle Seat

ABSTRACT

A wire harness connected to a sensor is positioned on a back surface of a pad of a vehicle seat supported by a panel. The vehicle seat (1) includes a panel (4); a pad (11, 51) supported by the panel; a skin material (12, 52) covering a front surface of the pad; and a sensor (32) provided between the front surface of the pad and the skin material for acquiring information on a seat occupant, wherein the pad is provided with a through hole (35, 58) passed from the front surface of the pad to a back surface of the pad, and a recess (45, 61) formed in the back surface of the pad and connected to the through hole, the wire harness connected to the sensor extending in the through hole and the recess.

TECHNICAL FIELD

The present invention relates to a vehicle seat.

BACKGROUND OF THE INVENTION

A vehicle seat having a seat sensor installed in the seat cushionthereof is known (for example, Patent Document 1). The seat sensor isprovided with a film-type pressure sensor positioned on the surface(upper surface) of the seat cushion pad. The pressure sensor is a sensorthat detects the pressure applied to the seating surface of the seatcushion, and detects that a seat occupant is seated. The pressure sensoris connected to a control unit via a wire harness that is passed througha hole vertically extending through the seat cushion pad and extends tothe back surface (lower surface) side of the seat cushion pad. Accordingto this arrangement, the wire harness can be positioned so as not tocontact the occupant.

A known seat sensor includes a plurality of pressure-sensitive switchesarranged in a seating region of a vehicle seat, and configured to turnon by the seating of an occupant (for example, Patent Document 2). Theseat sensor disclosed in Patent Document 2 includes a flexible sheetmaterial, a plurality of pressure-sensitive switches provided on thesheet material, and wiring provided on the sheet material and connectedto the pressure-sensitive switches. The pressure-sensitive switches arearranged so as to form a plurality of pairs arranged in the fore and aftdirection, each pair containing two pressure-sensitive switches arrangedlaterally one next to the other and connected in series so as to form anindividual sensor unit. The detection circuit becomes conductive and theseat sensor turns on when the two pressure-sensitive switches of atleast one of the sensor units are both turned on. Since the sensor unitsare arranged in the fore and aft direction, the seat sensor is able todetect the seating of an occupant without regard if the occupant isseated on a front part of the seating region or on a rear part of theseating region.

PRIOR ART DOCUMENT(S) Patent Document(s)

Patent Document 1: JP2017-65659A

Patent Document 1: JP2007-526844A

SUMMARY OF THE INVENTION Task to be Accomplished by the Invention

However, in the case of a rear seat, since the pads constituting theseat cushion and the seat back are supported by the vehicle body panel,an adequate space cannot be secured on the back side of the pad forplacing the wire harness.

In view of such a problem of the prior art, a primary object of thepresent invention to provide a vehicle seat having a pad supported by apanel which allows wire harness to be placed on the back side of thepad.

Means to Accomplish the Task

To achieve such an object, the present invention provides a vehicle seat(1), comprising: a panel (4); a pad (11, 51) supported by the panel; askin material (12, 52) covering a front surface of the pad; and a sensor(32) provided between the front surface of the pad and the skin materialfor acquiring information on a seat occupant, wherein the pad isprovided with a through hole (35, 58) passed from the front surface ofthe pad to a back surface of the pad, and a recess (45, 61) formed inthe back surface of the pad and connected to the through hole, thesensor being connected to a wire harness extending in the through holeand the recess.

Thus, in a vehicle seat having a pad supported by a panel, the recesscreates a space between the panel and the back surface of the pad sothat the wire harness can be placed in this space.

In this invention, preferably, the recess extends from the through holeto an edge of the back surface of the pad.

Thereby, the wire harness positioned on the back surface of the pad canbe drawn out to the side part of the pad.

In this invention, preferably, the surface of the panel (5) facesvertically, the pad (11) is placed on an upper surface of the panel soas to be rotatable around a center (X1) located in a rear end portionthereof, and the recess extends rearward from the through hole.Alternatively, the surface of the panel (6) faces in a fore and aftdirection, the pad (51) is positioned on a front surface of the panel soas to be rotatable around a center (X2) located in a lower end portionthereof, and the recess extends downward from the through hole.

Since the wire harness extends on the back surface of the pad from thethrough hole toward the rotation center, the distance between an end ofthe wire harness and the panel changes very little when the pad rotatesrelative to the panel so that the wire harness is prevented from beingpulled.

In this invention, preferably, the pad includes a plurality of members(14, 15) made of different materials, and the through hole is formed inone of the members.

Thereby, the through hole can be formed with ease.

In this invention, preferably, an air passage (37) extending from theback surface to the front surface is formed in the pad, and the throughhole is formed so as to avoid the air passage. Preferably, a lockingportion (41) for fixing a child seat is formed on the surface of thepad, and the through hole is formed so as to avoid the locking portion.Further, preferably, a heater cloth (43) having a heater wire isprovided on the front surface of the pad, and the through hole ispositioned so as to avoid the heater cloth.

Thereby, the interference of other components with the wire harness canbe minimized.

In this invention, preferably, one end of the through hole is providedat a position avoiding a pressure receiving area (30) defined as an areaon the surface of the pad to which a load of a seat occupant is directlyapplied. Preferably, the surface of the panel faces vertically, the padis positioned on an upper surface of the panel, and the through hole isprovided behind the pressure receiving area.

Thereby, the load of the occupant is prevented from being applied to thewire harness.

When a plurality of pressure sensors are arranged close to each other ona continuous sheet, a load applied within the detection range of acertain pressure sensor may produce a stress in the sheet so that adeformation of the sheet may be caused, and the other sensors mayerroneously detect the load. In view of this fact, another object of thepresent invention is to prevent such an erroneous detection by the seatsensor.

To achieve such an object, the present invention further provides a seatsensor (110) provided between an upper surface of a seat cushion pad(106) forming a seat cushion (102) of a vehicle seat (101) and a skinmaterial (107) covering the seat cushion pad, comprising: a flexiblesheet material (111); a plurality of pressure-sensitive switches (112)provided on the sheet material; and wiring (113) provided on the sheetmaterial and connected to the pressure-sensitive switches provided onthe sheet material, wherein the sheet material includes a laterallyextending main part (111A) and a plurality of branch parts (111B to111J) extending forward or rearward from the main part, thepressure-sensitive switches being provided at distal ends of therespective branch parts.

Since each pressure-sensitive switch is connected to the adjacentpressure-sensitive switch via the branch part, the main part, and thebranch part, the deformation of any particular branch part caused by theload applied to the pressure-sensitive switch on this branch part isless likely to be transmitted to the branch part on which the adjoiningpressure-sensitive switch is located. Therefore, erroneous detection bythe adjacent pressure-sensitive switches can be minimized.

In this invention, preferably, the main part extends from a left half ofthe occupant's seating region (105) to a right half thereof, and thebranch parts include a first branch part (111B) and a second branch part(111C) that are positioned in the left half of the seating regionlaterally spaced apart from each other, and a third branch part (111D)and a fourth branch part (111E) that are positioned in the right half ofthe seating region laterally spaced apart from each other. Further, thepressure-sensitive switches include a first pressure-sensitive switch(112B) provided at a tip of the first branch part, a secondpressure-sensitive switch (112C) provided at a tip of the second branchpart, a third pressure-sensitive switch (112D) provided at a tip of thethird branch part, and a fourth pressure-sensitive switch (112E)provided at a tip of the fourth branch, and the first to the fourthpressure-sensitive switches are arranged on a first imaginary straightline (L1) extending laterally.

Thus, even when the first to fourth pressure-sensitive switches arearranged close to each other along the lateral direction, erroneousdetection of the pressure-sensitive switches can be minimized.

In this invention, preferably, the hip point (HP) of the occupant islocated on the first imaginary straight line.

Thereby, the first to fourth pressure-sensitive switches can be arrangedin an area where the load of the occupant is most likely to be applied.

In this invention, preferably, the wiring connects the firstpressure-sensitive switch and the second pressure-sensitive switch inparallel to each other to form a first circuit (116), connects the thirdpressure-sensitive switch and the fourth pressure-sensitive switch inparallel to each other to form a second circuit (117), and connects thefirst circuit and the second circuit in series to each other.

The seat sensor can thereby reliably detect the occupant without regardto the difference in the stature/build of the occupant and the lateralshifting of the occupant's seating position.

In this invention, preferably, the first branch part and the firstpressure-sensitive switch are disposed leftward of the second branchpart and the second pressure-sensitive switch, and the third branch partand the third pressure-sensitive switch are arranged leftward of fourthbranch and the fourth pressure-sensitive switch. Further, the firstpressure-sensitive switch is configured to be turned on under a largerload than the second pressure-sensitive switch, and the fourthpressure-sensitive switch is configured to be turned on under a largerload than the third pressure-sensitive switch.

Thereby, the seat sensor is prevented from erroneously detecting anobject other than an occupant. More specifically, the laterally outerpressure-sensitive switches, or the first and fourth pressure-sensitiveswitches, are configured to be turned on under a larger load to detectan occupant of a larger physical stature/build. Since the laterallyouter pressure-sensitive switches are thus configured to be turned onunder a larger load, these pressure-sensitive switches are preventedfrom being turned on by an object lighter than a seat occupant.

In this invention, preferably, the first to fourth branch parts extendrearward from the main part, and the branch parts further include afifth branch part (111F) and a sixth branch part (111G) that extendforward in the left half of the seating region laterally spaced apartfrom each other, and a seventh branch part (111H) and an eighth branchpart (111J) that extend forward in the right half of the seating regionlaterally spaced apart from each other, and the pressure-sensitiveswitches include a fifth pressure-sensitive switch (112F) provided at atip of the fifth branch part, a sixth pressure-sensitive switch (112G)provided at a tip of the sixth branch part, a seventh pressure-sensitiveswitch (112H) provided at a tip of the seventh branch part; and aneighth pressure-sensitive switch (112J) provided at a tip of the eighthbranch part, wherein the fifth to eighth pressure-sensitive switches arearranged on a second imaginary straight line (L2) extending laterally.

By thus forming a rear switch row consisting of the first to fourthpressure-sensitive switches and a front switch row consisting of thefifth to eighth pressure-sensitive switches, the seat occupant can bereliably detected even when the seating position of the occupant isshifted to the front or to the rear.

In this invention, preferably, the wiring connects the fifthpressure-sensitive switch and the sixth pressure-sensitive switch inparallel to each other form a third circuit (118), and the seventhpressure-sensitive switch and the eighth sensor in parallel to eachother to form a fourth circuit (119) while the third circuit and thefourth circuit are connected in series to each other, the first circuitand the second circuit being connected in parallel to the third circuitand the fourth circuit.

The front switch row including the fifth to eighth pressure-sensitiveswitches can reliably detect the seat occupant even when the physicalstature/build of the seat occupant varies, or the occupant's seatingposition shifts in the lateral direction.

In this invention, preferably, the fifth branch part and the fifthpressure-sensitive switch are positioned leftward of the sixth branchpart and the sixth pressure-sensitive switch, and the seventh branchpart and the seventh pressure-sensitive switch are positioned leftwardof the eighth branch part and the eighth pressure-sensitive switch.Further, the fifth pressure-sensitive switch is configured to be turnedon under a larger load than the sixth pressure-sensitive switch, and theeighth pressure-sensitive switch is configured to be turned on under alarger load than the seventh pressure-sensitive switch.

The front switch row consisting of the fifth to eighthpressure-sensitive switches are prevented from erroneously detecting anobject other than a seat occupant.

In this invention, preferably, the first branch part and the fifthbranch part are linearly arranged in a fore and aft direction, thesecond branch part and the sixth branch part are linearly arranged inthe fore and aft direction, the third branch part and the seventh branchpart are linearly arranged in the fore and aft direction, and the fourthbranch part and the eighth branch part are linearly arranged in the foreand aft direction.

Thereby, the shape of the sheet material can be simplified.

In this invention, preferably, the branch parts include a ninth branchpart (111K) extending forward or rearward from the main part and havinga connecting portion (114) for connecting to an external wiring at a tipthereof, the connecting portion being positioned behind the secondimaginary straight line and forward of the first imaginary straightline.

Thereby, the overall fore and aft width of the seat sensor can beminimized, and the seat sensor can be formed as a compact unit.

In this invention, preferably, the vehicle seat forms a rear seat of anautomobile.

In this case, the seat sensor can correctly detect a seat occupantseating on the rear seat where the seating posture of the seat occupantcan largely vary.

When an object is placed on the seating surface, pressure is applied tothe seating surface, and the pressure is detected by the pressuresensor. Therefore, when only a pressure sensor is used, there may besome difficulty in distinguishing if a seat occupant is seated on theseating surface or an object is placed on the seating surface. Based onthis recognition, a primary object of the present invention is toprovide a vehicle seat that can distinguish if a seat occupant is seatedon the seating surface or an object is placed on the seating surface ina more accurate manner.

To achieve such an object, a certain embodiment of the present inventionconsists of a vehicle seat (201, 251, 261, 271) including a seat cushion(204) and a seat back (205) provided in a rear part of the seat cushion,the vehicle seat comprising: a pressure sensor (20) provided on the seatcushion; a capacitance sensor (240, 253, 254) provided on at least oneof the seat cushion and the seat back, and a determination unit (246)for determining if an occupant is seated according to a signal from thepressure sensor and a signal from the capacitance sensor.

If an occupant is seated or not can be determined from the signal fromthe pressure sensor and the signal from the capacitance sensor so thatthe distinction between the seating of an occupant and the placement ofan object on the seating surface can be made in a more reliable manner.

In this invention, preferably, the capacitance sensor is provided on theseat back.

Thus, the pressure sensor is provided on the seat cushion, and thecapacitance sensor is provided on the seat back. As a result, thepressure sensor and the capacitance sensor can be positioned so as notto interfere with each other without any difficulty, as compared withthe case where both the pressure sensor and the capacitance sensor areprovided on the seat cushion. Therefore, the two sensors are enabled tooperate without any risk of mutual interferences. Also, as compared withthe case where both the pressure sensor and the capacitance sensor areprovided on the seat cushion, wiring for the pressure sensor and thecapacitance sensor can be simplified.

In this invention, preferably, the capacitance sensor is provided at aposition corresponding to a hip (H) (lumbar region) of an occupant.

Since the capacitance sensor is positioned so as to be close to theseated occupant, the seating of the occupant can be detected with ahigher sensitivity.

In this invention, preferably, the seat cushion is provided with alateral listing groove (215) extending laterally for receiving a listingstrip of the skin material, and the pressure sensor includes a pair ofpressure sensors, one placed ahead of the listing groove and the otherplaced behind the listing groove.

Thereby, the assembling of the pressure sensors is facilitated. Also,deformation and displacement of the pressure sensors can be avoided.Further, by placing the pressure sensors ahead of and behind thelaterally extending listing groove, the pressure applied to the seatingsurface of the seat cushion can be detected over a wider range.

In this invention, preferably, the seat back is provided with a pair oflongitudinal listing grooves (236) each for receiving a listing strip ofthe skin material, and the capacitance sensor is provided between theleft and right longitudinal listing grooves.

Thereby, the assembling of the capacitance sensor is facilitated.Further, deformation and displacement of the capacitance sensor can beminimized.

In this invention, preferably, both the pressure sensor and thecapacitance sensor (253, 254) are provided on the seat cushion.

Thus, the capacitance sensor is provided on the seat cushion on whichthe occupant sits. Therefore, the capacitance sensor is positioned closeto the seating surface with which the occupant comes into contact whenseated so that the occupant can be detected by the capacitance sensorwith an increased sensitivity.

In this invention, preferably, the pressure sensor and the capacitancesensor are positioned so as to at least partly overlap with each otherin top view.

Thereby, the area of the seating surface occupied by the pressure sensorand the capacitance sensor can be minimized so that the discomfort thatmay be caused to the occupant due to the presence of the pressure sensorand the capacitance sensor can be minimized.

In this invention, preferably, the pressure sensor is positioned on topof the capacitance sensor in such a manner that the pressure sensor islocated within an outer periphery of the capacitance sensor in top view.

Thereby, the area of the seating surface occupied by the pressure sensorand the capacitance sensor can be minimized so that the discomfort thatmay be caused to the occupant due to the presence of the pressure sensorand the capacitance sensor can be minimized.

In this invention, preferably, the seat cushion is provided with alateral listing groove (215) extending laterally for receiving a listingstrip of the skin material, and the capacitance sensor includes a pairof capacitance sensors, one positioned ahead of the lateral listinggroove, and the other positioned behind the lateral listing groove, thepressure sensor including a pair of pressure sensors, one placed on topof one of the capacitance sensors, and the other placed on top of theother capacitance sensor.

Since the pressure sensors and the capacitance sensors are located aheadof and behind the lateral listing groove, the pressure applied to theseating surface of the seat cushion can be detected over a wider range.Since the pressure sensors and the capacitance sensors are located so asto avoid the lateral listing groove, the assembling of the pressuresensors to the seat cushion is facilitated, and the deformation and thedisplacement of these sensors when an occupant is seated can beminimized.

In this invention, preferably, the seat cushion is provided with alateral listing groove (215) extending laterally for receiving a listingstrip of the skin material, and the pressure sensor is positioned behindthe lateral listing groove, and the capacitance sensor is positionedahead of the lateral listing groove.

Since the pressure sensors and the capacitance sensors are both locatedclose to the seating surface, the seating of an occupant can be detectedwith a high sensitivity. Since the pressure sensors and the capacitancesensors are located so as to avoid the lateral listing groove, theassembling of the pressure sensors to the seat cushion is facilitated.Further, the deformation and the displacement of these sensors when anoccupant is seated can be minimized.

In this invention, preferably, the capacitance sensor is provided withan opening (263, 264) passed vertically therethrough, and positioned onthe seat cushion, and the pressure sensor is positioned inside theopening.

Since the pressure sensor is positioned inside the opening of thecapacitance sensor, the seating surface can be made more even so thatthe seating comfort can be improved.

In this invention, preferably, the upper surface of the pressure sensorand the upper surface of the capacitance sensor are flush with eachother.

Thereby, the seating surface becomes more even so that the seatingcomfort can be further improved.

In this invention, preferably, the seat cushion is provided with alateral listing groove (215) extending laterally for receiving a listingstrip of the skin material, and the capacitance sensor includes a pairof capacitance sensors, one positioned ahead of the lateral listinggroove and the other positioned behind the lateral listing groove, thepressure sensors being positioned in the openings of the capacitancesensors, respectively.

Since the pressure sensors and the capacitance sensors are positionedahead of and behind the lateral listing groove, the seating of anoccupant on the seating surface can be detected over a wider range.Since the pressure sensors and the capacitance sensors are located so asto avoid the lateral listing groove, the assembling of the pressuresensors and the capacitance sensors to the seat cushion is facilitated.Since the pressure sensors are positioned inside the openings of thecapacitance sensors, respectively, the seating surface can be made moreeven so that the seating comfort can be improved.

Effect of the Invention

According to the embodiment of the present invention which was mentionedearlier, in a vehicle seat having a pad supported by the panel, therecess creates a space between the panel and the back surface of the padso that the wire harness can be placed in this space.

When the recess extends from the through hole to an edge of the backsurface of the pad, the wire harness positioned on the back surface ofthe pad can be drawn out to the side part of the pad.

According to the embodiment in which the surface of the panel facesvertically, the pad is placed on an upper surface of the panel so as tobe rotatable around a center located in a rear end portion thereof, andthe recess extends rearward from the through hole, or alternatively, thesurface of the panel faces in a fore and aft direction, the pad isdisposed on a front surface of the panel so as to be rotatable around acenter located in a lower end portion thereof, and the recess extendsdownward from the through hole, the distance between the end of the wireharness and the panel changes very little when the pad rotates relativeto the panel so that the wire harness is prevented from being pulled.

When the pad includes a plurality of members made of differentmaterials, and the through hole is formed in one of the members, thethrough hole can be formed with ease.

According to an embodiment in which an air passage extending from theback surface to the front surface is formed in the pad, and the throughhole is formed so as to avoid the air passage, a locking portion forfixing a child seat is formed on the surface of the pad, and the throughhole is formed so as to avoid the locking portion, or a heater clothhaving a heater wire is provided on the front surface of the pad, andthe through hole opens at a position avoiding the heater cloth, theinterference of other components with the wire harness can be minimized.

According to an embodiment in which one end of the through hole isprovided at a position avoiding a pressure receiving area defined as anarea on the surface of the pad to which a load of a seat occupant isdirectly applied or, the surface of the panel faces vertically, the padis positioned on the upper surface of the panel, and the through hole isprovided behind the pressure receiving area, the load of the occupant isprevented from being applied to the wire harness.

When the sheet material includes a laterally extending main part and aplurality of branch parts extending forward or rearward from the mainpart, the pressure-sensitive switches being provided at distal ends ofthe respective branch parts, since each pressure-sensitive switch isconnected to the adjacent pressure-sensitive switch via the branch part,the main part, and the branch part, the deformation of any particularbranch part caused by the load applied to the pressure-sensitive switchon this branch part is less likely to be transmitted to the branch parton which the adjoining pressure-sensitive switch is located, erroneousdetection by the adjacent pressure-sensitive switches can be minimized.

When the branch parts include a first branch part and a second branchpart that are positioned in the left half of the seating regionlaterally spaced apart from each other, and a third branch part and afourth branch part that are positioned in the right half of the seatingregion laterally spaced apart from each other, and the first to thefourth pressure-sensitive switches are arranged on a first imaginarystraight line extending laterally, even when the first to fourthpressure-sensitive switches are arranged close to each other along thelateral direction, erroneous detection of the pressure-sensitiveswitches can be minimized.

When the hip point of the occupant is located on the first imaginarystraight line, the first to fourth pressure-sensitive switches can bearranged in an area where the load of the occupant is most likely to beapplied.

When the wiring connects the first pressure-sensitive switch and thesecond pressure-sensitive switch in parallel to each other to form afirst circuit, connects the third pressure-sensitive switch and thefourth pressure-sensitive switch in parallel to each other to form asecond circuit, and connects the first circuit and the second circuit inseries to each other, the seat sensor can reliably detect the occupantwithout regard to the difference in the stature/build of the occupantand the lateral shifting of the occupant's seating position.

When the first pressure-sensitive switch is configured to be turned onunder a larger load than the second pressure-sensitive switch, and thefourth pressure-sensitive switch is configured to be turned on under alarger load than the third pressure-sensitive switch, the seat sensor isprevented from erroneously detecting an object other than an occupant.Since the laterally outer pressure-sensitive switches are thusconfigured to be turned on under a larger load, these pressure-sensitiveswitches are prevented from being turned on by an object lighter than aseat occupant.

The branch parts may further include a fifth branch part and a sixthbranch part that extend forward in the left half of the seating regionlaterally spaced apart from each other, and a seventh branch part and aneighth branch part that extend forward in the right half of the seatingregion laterally spaced apart from each other, and the fifth to theeighth pressure-sensitive switches may be arranged on a second imaginarystraight line extending laterally. By thus forming the rear switch rowconsisting of the first to fourth pressure-sensitive switches and thefront switch row consisting of the fifth to eighth pressure-sensitiveswitches, the seat occupant can be reliably detected even when theseating position of the occupant is shifted to the front or to the rear.

When the wiring connects the fifth pressure-sensitive switch and thesixth pressure-sensitive switch in parallel to each other to form athird circuit, and the seventh pressure-sensitive switch and the eighthsensor in parallel to each other to form a fourth circuit while thethird circuit and the fourth circuit are connected in series to eachother, the first circuit and the second circuit being connected inparallel to the third circuit and the fourth circuit, the front switchrow including the fifth to eighth pressure-sensitive switches canreliably detect the seat occupant even when the physical stature/buildof the seat occupant varies, or the occupant's seating position shiftsin the lateral direction.

When the fifth pressure-sensitive switch is configured to be turned onunder a larger load than the sixth pressure-sensitive switch, and theeighth pressure-sensitive switch is configured to be turned on under alarger load than the seventh pressure-sensitive switch, the front switchrow consisting of the fifth to eighth pressure-sensitive switches areprevented from erroneously detecting an object other than a seatoccupant.

When the first branch part and the fifth branch part are linearlyarranged in a fore and aft direction, the second branch part and thesixth branch part are linearly arranged in the fore and aft direction,the third branch part and the seventh branch part are linearly arrangedin the fore and aft direction, and the fourth branch part and the eighthbranch part are linearly arranged in the fore and aft direction, theshape of the sheet material can be simplified.

When the connecting portion provided at the tip of the ninth branch partis positioned behind the second imaginary straight line and forward ofthe first imaginary straight line, the overall fore and aft width of theseat sensor can be minimized, and the seat sensor can be formed as acompact unit.

When the vehicle seat forms a rear seat of an automobile, the seatsensor can correctly detect a seat occupant seating on the rear seatwhere the seating posture of the seat occupant can largely vary.

When the vehicle seat comprises a pressure sensor provided on the seatcushion, a capacitance sensor provided on at least one of the seatcushion and the seat back, and a determination unit for determining ifan occupant is seated according to a signal from the pressure sensor anda signal from the capacitance sensor, the distinction between theseating of an occupant and the placement of an object on the seatingsurface can be made in a more reliable manner.

In this embodiment, when the capacitance sensor is provided on the seatback, the pressure sensor and the capacitance sensor can be positionedso as not to interfere with each other without any difficulty, ascompared with the case where both the pressure sensor and thecapacitance sensor are provided on the seat cushion. Also, as comparedwith the case where both the pressure sensor and the capacitance sensorare provided on the seat cushion, wiring for the pressure sensor and thecapacitance sensor can be simplified.

In this embodiment, when the capacitance sensor is provided at aposition corresponding to a hip of an occupant, since the capacitancesensor is positioned so as to be close to the seated occupant, theseating of the occupant can be detected with a higher sensitivity.

In this embodiment, when the seat cushion is provided with a laterallisting groove extending laterally for receiving a listing strip of theskin material, and the pressure sensor includes a pair of pressuresensors, one placed ahead of the listing groove and the other placedbehind the listing groove, the assembling of the pressure sensors isfacilitated. Also, deformation and displacement of the pressure sensorscan be avoided. Further, by placing the pressure sensors ahead of andbehind the laterally extending listing groove, respectively, thepressure applied to the seating surface of the seat cushion can bedetected over a wider range.

In this embodiment, when the seat back is provided with a pair oflongitudinal listing grooves each for receiving a listing strip of theskin material, and the capacitance sensor is provided between the leftand right longitudinal listing grooves, the assembling of thecapacitance sensor is facilitated. Further, deformation and displacementof the capacitance sensor can be minimized.

In this embodiment, when both the pressure sensor and the capacitancesensor are provided on the seat cushion, the capacitance sensor ispositioned close to the seating surface with which the occupant comesinto contact when seated so that the occupant can be detected by thecapacitance sensor with an increased sensitivity.

In this embodiment, when the pressure sensor and the capacitance sensorare positioned so as to at least partly overlap with each other in topview, the area of the seating surface occupied by the pressure sensorand the capacitance sensor can be minimized so that the discomfort thatmay be caused to the occupant due to the presence of the pressure sensorand the capacitance sensor can be minimized.

In this embodiment, when the pressure sensor is positioned on top of thecapacitance sensor in such a manner that the pressure sensor is locatedwithin an outer periphery of the capacitance sensor in top view, thearea of the seating surface occupied by the pressure sensor and thecapacitance sensor can be minimized so that the discomfort that may becaused to the occupant due to the presence of the pressure sensor andthe capacitance sensor can be minimized.

In this embodiment, when the seat cushion is provided with a laterallisting groove extending laterally for receiving a listing strip of theskin material, and the capacitance sensor includes a pair of capacitancesensors, one positioned ahead of the lateral listing groove, and theother positioned behind the lateral listing groove, the pressure sensorincluding a pair of pressure sensors, one placed on top of one of thecapacitance sensors, and the other placed on top of the othercapacitance sensor, since the pressure sensors and the capacitancesensors are located ahead of and behind the lateral listing groove, thepressure applied to the seating surface of the seat cushion can bedetected over a wider range. Since the pressure sensors and thecapacitance sensors are located so as to avoid the lateral listinggroove, the assembling of the pressure sensors to the seat cushion isfacilitated, and the deformation and the displacement of these sensorswhen an occupant is seated can be minimized.

In this embodiment, when the seat cushion is provided with a laterallisting groove extending laterally for receiving a listing strip of theskin material, and the pressure sensor is positioned behind the laterallisting groove, and the capacitance sensor is positioned ahead of thelateral listing groove, since the pressure sensor and the capacitancesensor are both located close to the seating surface, the seating of anoccupant can be detected with a high sensitivity. Since the pressuresensor and the capacitance sensor are located so as to avoid the laterallisting groove, the assembling of the pressure sensors to the seatcushion is facilitated. Further, the deformation and the displacement ofthese sensors when an occupant is seated can be minimized.

In this embodiment, when the capacitance sensor is provided with anopening passed vertically therethrough, and placed in the seat cushion,and the pressure sensor is positioned inside the opening, since thepressure sensor is positioned inside the opening of the capacitancesensor, the seating surface can be made more even so that the seatingcomfort can be improved.

In this embodiment, when the upper surface of the pressure sensor andthe upper surface of the capacitance sensor are flush with each other,the seating surface becomes more even so that the seating comfort can befurther improved.

In this embodiment, when the seat cushion is provided with a laterallisting groove extending laterally for receiving a listing strip of theskin material, and the capacitance sensor includes a pair of capacitancesensors, one positioned ahead of the lateral listing groove and theother positioned behind the lateral listing groove, the pressure sensorsbeing positioned in the openings of the capacitance sensors,respectively, since the pressure sensors and the capacitance sensors arepositioned ahead of and behind the lateral listing groove, the seatingof an occupant on the seating surface can be detected over a widerrange. Since the pressure sensors and the capacitance sensors arelocated so as to avoid the lateral listing groove, the assembling of thepressure sensors and the capacitance sensors to the seat cushion isfacilitated. Since the pressure sensors is positioned inside theopenings of the capacitance sensors, respectively, the seating surfacecan be made more even so that the seating comfort can be improved.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a seat according to a first embodimentof the present invention;

FIG. 2 is a sectional view of a seat cushion pad of the firstembodiment;

FIG. 3 is an exploded perspective view of the seat cushion pad of thefirst embodiment;

FIG. 4 is a plan view of the seat cushion pad of the first embodiment;

FIG. 5 is a bottom view of the seat cushion pad of the first embodiment;

FIG. 6 is a plan view of the seat cushion pad according to a secondembodiment of the present invention;

FIG. 7 is a plan view of rear seat according to a third embodiment ofthe present invention;

FIG. 8 is a side view of the rear seat of the third embodiment;

FIG. 9 is a plan view of a seat sensor provided in the rear seat of thethird embodiment;

FIG. 10 is a circuit diagram of the seat sensor of the third embodiment

FIG. 11 is a perspective view of a vehicle seat according to a fourthembodiment of the present invention;

FIG. 12 is a side view of the vehicle seat of the fourth embodiment andan enlarged sectional view of a part thereof adjacent to a first laterallisting groove;

FIG. 13 is a top view of the vehicle seat of the fourth embodiment;

FIG. 14 is a circuit diagram of a pressure-sensitive sensor sheet of thefourth embodiment;

FIG. 15 is a flowchart of a determination process;

FIG. 16 shows top views of a vehicle sheet when an occupant is seated in(A) a rear part, (B) a front part, and (C) a right part of a seatingsurface, and (D) when a sack of rice is placed on the seating surface;

FIG. 17 is a top view of a vehicle seat according to a fifth embodimentof the present invention;

FIG. 18 is a top view of a vehicle seat according to a sixth embodimentof the present invention; and

FIG. 19 is a top view of a vehicle seat according to a seventhembodiment of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT(S) First Embodiment

A vehicle seat as applied to a rear seat of an automobile according to afirst embodiment of the present invention is described in the followingwith reference to the appended drawings. In the following description,the left and right directions are defined from the viewpoint of anoccupant seated on the seat.

As shown in FIG. 1, the seat 1 is a bench seat on which three people canbe seated. The seat 1 is provided with a seat cushion 2 and a seat back3 extending upward from a rear end of the seat cushion 2. As shown inFIG. 2, the seat 1 is supported by a vehicle body panel 4 which forms avehicle body of the automobile. The vehicle body panel 4 is formed bystamp-forming steel sheet, and has a floor portion 5 having a verticallyfacing surface, and a wall portion 6 which extends upward from the rearedge of the floor portion 5 and has a surface facing in the fore and aftdirection. The wall portion 6 separates a cabin and a luggage space fromeach other. The seat cushion 2 is supported on the upper surface of thefloor portion 5, and the seat back 3 is supported on the front surfaceof the wall portion 6.

The seat cushion 2 includes a seat cushion pad 11 supported by the floorportion 5 and a skin material 12 that covers a front surface (uppersurface) of the seat cushion pad 11. As shown in FIGS. 2 and 3, the seatcushion pad 11 is formed by combining a plurality of members made ofdifferent materials. The seat cushion pad 11 has a rigid part 14 thatforms the outer periphery of the back part (lower part) thereof, and asoft part 15 that forms the front part (upper part) thereof and thecentral part of the lower part thereof. The soft part 15 has a higherflexibility than the rigid part 14 and is connected to the rigid part14. The rigid part 14 is, for example, EPP (foamed polypropylene), andthe soft part 15 is, for example, urethane foam. Due to the structure inwhich the soft part 15 is supported by the rigid part 14, the shape ofthe seat cushion pad 11 can be maintained. In another embodiment, inorder to maintain the shape of the seat cushion pad 11, a reinforcingmaterial such as wire is provided inside at least one of the soft part15 and the rigid part 14. Optionally, a frame structure may be providedfor supporting the soft part 15.

The seat cushion pad 11 is rotatably supported by the floor portion 5about a rotational axis X1 extending laterally at the rear end thereof.The seat cushion pad 11 is preferably rotatably supported by a bracketprovided on the floor portion 5. The seat cushion pad 11 can rotateabout the rotational axis X1 between a normal position where the backsurface (lower surface) thereof contacts the upper surface of the floorportion 5 to allow an occupant to be seated thereon, and a tip-upposition where the front part thereof is moved upward from the normalposition. In the normal position, the front end of the seat cushion pad11 may be locked to the floor portion 5.

As shown in FIGS. 3 and 4, a listing groove 20 for receiving listingstrips of the skin material 12 is formed on the surface (upper surface)of the seat cushion pad 11. A wire for engaging hooks of the listingstrips provided on the back surface of the skin material 12 is providedin each section of the listing groove 20. Each wire is embedded in thesoft part 15 and is exposed outside in the listing groove 20. Thelisting groove 20 formed in a left part of the surface of the seatcushion pad 11 corresponding to the left seat includes a pair oflongitudinal grooves 21 and 22 provided on either side thereof and apair of lateral grooves 23 and 24 provided on in a front part and a rearpart thereof, respectively.

The left and right longitudinal grooves 21 and 22 extend in the fore andaft direction in a laterally spaced relationship in parallel to eachother. The spacing between the left and right longitudinal grooves 21and 22 is preferably larger than the distance between the hip joints ofa general adult male. The front ends of the left and right longitudinalgrooves 21 and 22 reach the front edge of the seat cushion pad 11. Thefront lateral groove 23 extends laterally at a position ahead of the hipjoints of the occupant in the proper sitting position, and is connectedto the left and right longitudinal grooves 21 and 22. The front lateralgroove 23 is provided at a central part of the surface of the seatcushion pad 11 with respect to the fore and aft direction. The rearlateral groove 24 extends laterally at a position behind the hip jointsof the seated occupant in the proper seating position, and is connectedto the left and right longitudinal grooves 21 and 22. The rear lateralgroove 24 is provided at a position of the surface of the seat cushionpad 11 in a range of 10% to 30% of the entire longitudinal length fromthe rear edge with respect to the fore and aft direction.

The surface of the seat cushion pad 11 includes a left inclined portion26 inclining upward from the left longitudinal groove 21 toward the leftend thereof, and a right inclined portion 17 inclining upward from theright longitudinal groove 22 toward the right end thereof, and a rearinclined portion 28 inclining upward from the rear lateral groove 24toward the rear end thereof. An area on the surface of the seat cushionpad 11 to which the load of the occupant is directly applied is definedas a pressure receiving area 30. In the present embodiment, the pressurereceiving area 30 corresponds to a region surrounded by the left andright longitudinal grooves 21 and 22 and the rear lateral groove 24.

As shown in FIGS. 2 and 4, a sensor 32 is positioned between the frontsurface of the seat cushion pad 11 and the skin material 12 foracquiring information on the seat occupant. The sensor 32 may include aload sensor (pressure sensor) for detecting the load of the seatedperson, a blood pressure sensor for detecting the blood pressure of theseated person, a pulse sensor for detecting the pulse of the seatedperson, a sweat sensor for detecting the sweat of the seated person, anodor sensor that detects the odor of the seated person, a bodytemperature sensor that detects the body temperature of the seatedperson, or the like. The sensor 32 is preferably formed in a film shape,and preferably extends along the front surface of the seat cushion pad11.

In the present embodiment, the sensor 32 consists of a load sensor thatdetects the load of the seat occupant. The sensor 32 includes a flexiblefilm 32A and thin film-like detection units 32B provided on the film32A. The detection units 32B may each consist of, for example, apiezoelectric element or a thin film switch in which two metal platesare placed opposite to each other with a gap therebetween, so that whena load is applied, the two metal plates bend and come into contact witheach other to conduct. The film 32A is provided along the front surfaceof the seat cushion pad 11. The film 32A extends from the pressurereceiving area 30 to the rear inclined portion 28, and passes over thelateral groove 24 on the rear side. The skin material 12 is pulled intothe rear lateral groove 24 on either lateral side of the film 32A inorder to avoid interference with the film 32A. The front end of the film32A is branched and extends to in both the leftward and rightwarddirections. The detection units 32B are provided at the left and rightends of the front end of the film 32A, respectively, and are positionedin the pressure receiving area 30. The film 32A is provided with signallines extending from the detection units 32B. The film 32A may be aflexible printed circuit board or the like. A wire harness 33 fortransmitting the detection signal from the detection units 32B isconnected to a rear end part of the film 32A of the sensor 32.

A harness passage 35 is formed in the seat cushion pad 11 as a throughhole passed therethrough from the front surface to the back surface. Thewire harness 33 connected to the sensor 32 extends from the front sideof the seat cushion pad 11 to the back side of the seat cushion pad 11through the wire harness passage 35. The open end of the wire harnesspassage 35 on the front surface side is provided at a position avoidingthe pressure receiving area 30. In the present embodiment, the open endof the wire harness passage 35 on the front surface side is provided inthe rear inclined portion 28. The wire harness passage 35 may be formedonly in the soft part 15, or may be formed in the soft part 15 and therigid part 14. By forming the wire harness passage 35 only in the softpart 15 while avoiding the rigid part 14, the forming process for thewire harness passage 35 is facilitated. In the present embodiment, thewire harness passage 35 extends vertically and is passed through boththe soft part 15 and the rigid part 14 so that the open end on the backsurface side is formed in the rigid part 14. The diameter of the part35A of the wire harness passage 35 formed in the rigid part 14 is largerthan the diameter of the part 35B of the wire harness passage 35 formedin the soft part 15. Thus, the wire harness passage 35 consists of astepped hole in which the diameter of the part 35A of the wire harnesspassage 35 on the back surface side is increased stepwise with respectto the part 35B of the wire harness passage 35 on the front surfaceside. In another embodiment, the wire harness passage 35 may extendobliquely with respect to the vertical direction. By causing the wireharness passage 35 to extend obliquely, the wire harness passage 35 canbe formed only in the soft part 15 while avoiding the rigid part 14.

An air passages 37 extends in the seat cushion pad 11 from the backsurface thereof to the front surface thereof. The air passage 37includes a collecting portion 37A opening on the back surface of theseat cushion pad 11, and a branch part 37B branched from the collectingportion 37A and opening on the front surface. A blower 38 is provided atthe open end of the collecting portion 37A. A ventilation groove 39 isformed in the floor portion 5 of the vehicle body panel 4 at a positioncorresponding to the open end of the collecting portion 37A. Theventilation groove 39 extends in the fore and aft direction, andcommunicates with the open end of the collecting portion 37A at the rearend thereof, and communicates with the internal space of the cabin atthe front end thereof. The skin material 12 has air permeability. As theblower 38 rotates, the air drawn from the passenger compartment flowsthrough the ventilation groove 39, the collecting portion 37A, and thebranch part 37B in that order, and passes through the skin material 12.The air is then discharged upward from the seat cushion 2. The wireharness passage 35 is formed so as to avoid the air passage 37. Inanother embodiment, the wire harness passage 35 at least partly overlapswith the air passage 37. The ventilation groove 39 may be formed on theback surface of the seat cushion pad 11 by suitably recessing thecorresponding part thereof, instead of the floor portion 5.

A rear end part of the front surface of the seat cushion pad 11 isprovided with a pair of locking portions 41 for securing child seatslaterally one next to the other. Each locking portion 41 includes agroove formed in the seat cushion pad 11 and a striker placed inside thegroove. The locking portions 41 may be configured to comply with theinternational standard ISO-FIX. The wire harness passage 35 is formed soas to avoid the respective locking portions 41.

As shown in FIGS. 2 and 5, the back surface of the seat cushion pad 11is provided with a recess 45 connected to the open end of the wireharness passage 35 on the back surface side of the seat cushion pad 11.The recess 45 and the floor portion 5 of the vehicle body panel 4jointly form a space for receiving the wire harness 33 therein. Therecess 45 has a groove shape and extends rearward from the wire harnesspassage 35. More specifically, the recess 45 extends from the wireharness passage 35 toward the side of the rotational axis X1 of the seatcushion pad 11. The rear end of the recess 45 may reach the rear edge ofthe seat cushion pad 11. The recess 45 may be dimensioned so as toreceive an electronic component such as a connector of the wire harness33 or a microcomputer to which the wire harness 33 is connected.

The wire harness 33 extends rearward from the sensor 32 provided on thefront surface of the seat cushion pad 11 along the front surface of theseat cushion pad 11, reaches the back side of the seat cushion pad 11via the wire harness passage 35, and then extends to the rear edge ofthe seat cushion pad 11 via the recess 45.

As shown in FIG. 2, the seat back 3 includes a seat back pad 51supported by the wall portion 6 of the vehicle body panel 4, and a skinmaterial 52 covering a surface (front surface) of the seat back pad 51.The seat back pad 51 has a rigid part 53 and a soft part 54, similarlyto the seat cushion pad 11.

The seat back pad 51 is rotatably supported at the lower end thereof bythe wall portion 6 about a rotational axis X2 extending laterally. Theseat back pad 51 may be supported by a bracket provided on the wallportion 6 so as to be rotatable around the rotational axis X2. The seatback pad 51 rotates about the rotational axis X2 between a normalposition in which the back surface (rear surface) is in contact with thefront surface of the wall portion 6, and a forward tilt position inwhich the upper portion of the seat back pad 51 is positioned forwardwith respect to the normal position. In the normal position, the upperend of the seat back pad 51 is preferably locked to the wall portion 6.In another embodiment, the seat back pad 51 is rotatably supported bythe seat cushion pad 11 instead of the wall portion 6.

A listing groove is formed on the surface of the seat back pad 51,similarly to the seat cushion pad 11. A sensor 57 is placed between thefront surface of the seat back pad 51 and the skin material 52 foracquiring information on the occupant. The sensor 57 may be similar tothe sensor 32 provided on the seat cushion pad 11.

A harness passage 58 penetrates the seat back pad 51 from the frontsurface to the back surface. A wire harness 59 connected to the sensor57 extends from the front side of the seat back pad 51 to the back sideof the seat cushion pad 11 through the wire harness passage 58. The wireharness passage 58 can be positioned similarly to the wire harnesspassage 35 of the seat cushion pad 11.

On the back surface of the seat back pad 51 is formed a recess 61communicating with the open end on the back surface side of the wireharness passage 58. A space is defined between the recess 61 and thewall portion 6 of the vehicle body panel 4 to receive the wire harness59 therein. The recess 61 has a groove shape and extends downward fromthe wire harness passage 58. More specifically, the recess 61 extendsfrom the wire harness passage 58 toward the rotational axis X2 of theseat back pad 51. The lower end of the recess 61 may reach the loweredge of the seat back pad 51.

The effect of the seat 1 according to the foregoing embodiment isdiscussed in the following. Owing to the recess 45 provided on the backsurface of the seat cushion pad 11, a space is created between the floorportion 5 of the vehicle body panel 4 and the back surface of the seatcushion pad 11 so that the wire harness 33 can be positioned in thisspace. Similarly, a space is created between the wall portion 6 of thevehicle body panel 4 and the back surface of the seat back pad 51 by therecess 61 provided on the back surface of the seat back pad 51 so thatthe wire harness 59 can be positioned in this space.

Since the recess 45 of the seat cushion pad 11 extends rearward from thewire harness passage 35, or in other words, toward the rotational axisX1 of the seat cushion pad 11, when the seat cushion pad 11 is rotatedrelative to the floor portion 5, the distance between the floor portion5 and the wire harness 33 does not change to any significant extent sothat the wire harness 33 is prevented from being pulled excessively.Similarly, the recess 61 of the seat back pad 51 extends downward fromthe wire harness passage 58, or in other words, toward the rotationalaxis X2 of the seat back pad 51 so that the wire harness 59 is preventedfrom being pulled excessively.

Since the wire harness passage 35 opens at a position (the rear inclinedportion 28) on the front surface of the seat cushion pad 11 that avoidsthe pressure receiving area 30, the load of the occupant is preventedfrom being applied to the wire harness 33. The same is true with theseat back 3.

Second Embodiment

A seat 70 according to a second embodiment of the present invention isdescribed in the following. As shown in FIG. 6, the seat 70 of thesecond embodiment is different from the seat 1 of the first embodimentin that the seat 70 does not have the air passage 37, and has a heatercloth 72. The seat 70 of the second embodiment is otherwise similar tothe seat 1 of the first embodiment. Therefore, in the followingdisclosure, the parts having similar structures are denoted with likenumerals without necessarily repeating the description of such parts.

The heater cloth 72 incorporated with a heater wire 73 is placed betweenthe front surface of the seat cushion pad 11 and the skin material 12.The heater cloth 72 has a substantially rectangular main body 72Apositioned in the pressure receiving area 30, and a pair of connectingportions 72B extending rearward from the rear edge of the main body 72Aalong either side of the main body 72A. The heater cloth 72 extends intothe lateral grooves 23 and 24 and is passed under the skin material 12.The connecting portions 72B extend from the front side to the back sideof the seat cushion pad 11 along the rear end of the seat cushion pad11.

The main body 72A of the heater cloth 72 is positioned so as to overlapwith the detection units 32B of the sensor 32 and a front part of thefilm 32A. Meanwhile, the open end of the wire harness passage 35 on thefront side is positioned so as to avoid the heater cloth 72. The openend of the wire harness passage 35 on the front surface side ispositioned in a region defined by the rear edge of the main body 72A andthe left and right connecting portions 72B.

Third Embodiment

A seat sensor of a vehicle seat as applied to a seat sensor for a secondrow or third row rear seat according to a third embodiment of thepresent invention is described in the following.

As shown in FIG. 7, the seat 101 includes a seat cushion 102 provided ona floor of an automobile, a pair of seat backs 103 supported on a rearportion of the seat cushion 102 laterally one next to the other, and apair of headrests 104 provided on the upper parts of the respective seatbacks 103. The seat cushion 102 extends laterally so as to form a pairof seating regions 105 for seating a pair of occupants

As shown in FIG. 8, the seat cushion 102 includes a seat cushion pad 106and a skin material 107 that covers the front surface of the seatcushion pad 106. The seat cushion pad 106 may be directly supported on afloor panel of an automobile, or may be supported on a frame structuresupported on the floor panel. In the present embodiment, a sheet-likewadding material 108 is provided between the skin material 107 and theseat cushion pad 106. The wadding material 108 is optional, and may beomitted.

As shown in FIG. 8, the upper surface of each seating region 105 of theseat cushion 102 is inclined downward toward the rear end thereof. Eachseating region 105 supports an occupant's buttocks and thighs.

As shown in FIGS. 7 and 9, each seating region 105 is provided with aseat sensor 110 for detecting an occupant's seating. The seat sensor 110essentially consists of a switch that is turned on when an occupant isseated and cut off when no occupant is seated. The seat sensor 110includes a flexible sheet material 111, a plurality ofpressure-sensitive switches 112 provided on the sheet material 111, andwiring 113 provided on the sheet material 111 and connected to thepressure-sensitive switches.

The sheet material 111 is placed between the wadding material 108 andthe seat cushion pad 106. The sheet material 111 may be, for example, aflexible printed circuit board. The sheet material 111 includes a mainpart 111A extending laterally, and a plurality of branch parts 111B to111J extending forward or rearward from the main part 111A. The mainpart 111A extends linearly from the left half to the right half of theoccupant's seating region 105. The laterally central part of the mainpart 111A coincides with a line extending in the fore and aft directionin a laterally central part of the seating region 105.

In the present embodiment, the branch parts 111B to 111J include a firstbranch part 111B, a second branch part 111C, a third branch part 111D,and a fourth branch part 111E extending rearward from the main part111A. The branch parts 111B to 111J further include a fifth branch part111F, a sixth branch part 111G, a seventh branch part 111H, and aneighth branch part 111J extending forward from the main part 111A. Inthe present embodiment, the first to eighth branch parts 111B to 111Jare orthogonal to the main part 111A.

The first branch part 111B, the second branch part 111C, the thirdbranch part 111D, and the fourth branch part 111E are arranged laterallyfrom left to right in that order in a mutually spaced apartrelationship. The first branch part 111B and the second branch part 111Care positioned in the left half of the seating region 105, and the thirdbranch part 111D and the fourth branch part 111E are positioned in theright half of the seating region. The lateral distance between the firstbranch part 111B and the second branch part 111C is equal to the lateraldistance between the third branch part 111D and the fourth branch part111E. The lateral distance between the second branch part 111C and thethird branch part 111D is larger than the distance between the lateraldistance between the first branch part 111B and the second branch part111C. The lateral distance between the second branch part 111C and thethird branch part 111D is preferably larger than the distance betweenthe first and second branch parts 111B and 111C by the factor of two tothree.

The fifth branch part 111F, the sixth branch part 111G, the seventhbranch part 111H, and the eighth branch part 111J are arranged laterallyfrom left to right in that order in a mutually spaced apartrelationship. The fifth branch part 111F and the sixth branch part 111Gare arranged on the left half of the seating region 105, and the seventhbranch part 111H and the eighth branch part 111J are arranged on theright half of the seating region. The fifth branch part 111F is linearlyarranged in front of the first branch part 111B, the sixth branch part111G is linearly arranged in front of the second branch part 111C, theseventh branch part 111H is linearly arranged in front of the thirdbranch part 111D, and the eighth branch part 111J is linearly arrangedin front of the fourth branch part 111E. The lateral distance betweenthe fifth branch part 111F and the sixth branch part 111G and thelateral distance between the seventh branch part 111H and the eighthbranch part 111J are each equal to the lateral distance between thefirst branch part 111B and the second branch part 111C. The lateraldistance between the sixth branch part 111G and the seventh branch part111H is equal to the distance between the second branch part 111C andthe third branch part 111D.

The first to fourth branch parts 111B to 111E have the same length. Thefifth to eighth branch parts 111F to 111J have the same length. Thefirst to eighth branch parts 111B to 111J may all have an equal length.

A ninth branch part 111K extends forward from a laterally central partof the main part 111A. The front end of the ninth branch part 111K isprovided with a connecting portion 114 for connection to a wire harness121 to provide as an external wiring. The ninth branch part 111K ispreferably shorter than the fifth to eighth branch parts 111F to 111J.

In the present embodiment, the pressure-sensitive switches 112 includefirst to eighth pressure-sensitive switches 112B to 112J. Eachpressure-sensitive switch 112 is a membrane switch, and is provided on aframe-like spacer sheet, a pair of contact sheets stacked one over theother via the frame-like spacer sheet, and a pair of electric contactsprovided on opposing surfaces of the contact sheets, respectively. Whenthe pressure-sensitive switch 112 receives an external load, the contactsheets bend with the result that the two contacts come into contact witheach other to be in a conductive state or the pressure-sensitive switch112 is turned on. The pressure at which the contacts come into contactwith each other can be changed by adjusting the size and thickness ofthe contacts, the thickness and shape of the spacer, the stiffness ofthe contact sheets, and the like. The pressure-sensitive switches 112may also be of any other configuration as long as it is a switch thatconducts electricity upon detecting pressure.

As shown in FIG. 9, the first pressure-sensitive switch 112B is providedat the tip end (rear end) of the first branch part 111B, the secondpressure-sensitive switch 112C is provided at the tip end (rear end) ofthe second branch part 111C, the third pressure-sensitive switch 112D isprovided at the tip end (rear end) of the third branch part 111D, thefourth pressure-sensitive switch 112E is provided at the tip end (rearend) of the fourth branch part 111E, the fifth pressure-sensitive switch112F is provided at the tip (tip end) of the fifth branch part 111F, thesixth pressure-sensitive switch 112G is provided at the tip (tip end) ofthe sixth branch part 111G, the seventh pressure-sensitive switch 112His provided at the tip (tip end) of the seventh branch part 111H, andthe eighth pressure-sensitive switch 112J is provided at the tip (tipend) of the eighth branch part 111J.

The first to fourth pressure-sensitive switches 112B to 112E arearranged on a first imaginary straight line L1 extending laterally. Thefifth to eighth pressure-sensitive switches 112F to 112J are arranged ona second imaginary straight line L2 extending also extending laterally.The first imaginary straight line L1, the second imaginary straight lineL2, and the main part 111A are arranged in parallel with each other. Thefirst imaginary straight line L1 is positioned behind the main part111A, and the second imaginary straight line L2 is positioned ahead ofthe main part 111A.

The occupant's hip point HP is positioned on the first imaginarystraight line L1. The hip point HP is defined by the American SAEstandard J-826, and is given by the rotational center points (theposition of the hip joints) between the torso and the thighs of athree-dimensional mannequin. In plan view, the hip point is a centralpoint of a line segment connecting the two rotational center points.

Preferably, the front edge of the connecting portion 114 provided at thetip end of the ninth branch part 111K is positioned behind the secondimaginary straight line L2 and forward of the first imaginary straightline L1. Thereby, the overall fore and aft width of the seat sensor 110can be reduced.

As shown in FIG. 10, the wiring 113 provided on the sheet material 111connects the first to eighth pressure-sensitive switches 112B to 112J soas to form a detection circuit 115. The wiring 113 connects the firstpressure-sensitive switch 112B and the second pressure-sensitive switch112C in parallel to each other to form a first circuit 116, connects thethird pressure-sensitive switch 112D and the fourth pressure-sensitiveswitch 112E in parallel to each other so as to form a second circuit117, and connects the first circuit 116 and the second circuit 117 inseries to each other. Further, the wiring 113 connects the fifthpressure-sensitive switch 112F and the sixth pressure-sensitive switch112G in parallel to each other to form a third circuit 118, connects theseventh pressure-sensitive switch 112H and the eighth pressure-sensitiveswitch 112J in parallel to each other to form a fourth circuit 119, andconnects the third circuit 118 and the fourth circuit 119 in series toeach other. The detection circuit 115 is formed by connecting the firstcircuit 116 and the second circuit 117 and the third circuit 118 and thefourth circuit 119 in parallel to one another via the wiring 113. Thetwo ends of the wiring 113 are provided at the connecting portion 114,and are connected to a control unit 122 via a wire harness 121. The wireharness 121 is passed through a passage 123 vertically penetrating theseat cushion pad 106, and extend under the seat cushion pad 106. Theupper end of the passage 123 may be positioned on the second imaginarystraight line L2 or behind the second imaginary straight line L2.Thereby, the passage 123 can be formed close to the seat sensor 110 sothat the area on the upper surface of the seat cushion pad 106 occupiedby the wire harness 121 can be minimized. Further, the seat sensor 110and the passage 123 can be arranged compactly.

The first pressure-sensitive switch 112B is configured to be turned onunder a larger load than the second pressure-sensitive switch 112C, andthe fourth pressure-sensitive switch 112E is configured to be turned onunder a larger load than the third pressure-sensitive switch 112D.Preferably, the first pressure-sensitive switch 112B and the fourthpressure-sensitive switch 112E have a same ON load, and the secondpressure-sensitive switch 112C and the third pressure-sensitive switch112D have a same ON load. The fifth pressure-sensitive switch 112F isconfigured to be turned on at a larger load than the sixthpressure-sensitive switch 112G, and the eighth pressure-sensitive switch112J is configured to be turned on under a larger load than the seventhpressure-sensitive switch 112H. The fifth pressure-sensitive switch 112Fand the eighth pressure-sensitive switch 112J may have a same ON load,and the sixth pressure-sensitive switch 112G and the seventhpressure-sensitive switch 112H may have a same ON load. Preferably, thefirst pressure-sensitive switch 112B and the fifth pressure-sensitiveswitch 112F have a same ON load, and the second pressure-sensitiveswitch 112C and the sixth pressure-sensitive switch 112G have a same ONload.

An example of positioning of the pressure-sensitive switches 112 isgiven in the following. The lateral distance between the secondpressure-sensitive switch 112C and the third pressure-sensitive switch112D is preferably between 60 mm and 100 mm. The distance between thefirst pressure-sensitive switch 112B and the second pressure-sensitiveswitch 112C and the distance between the third pressure-sensitive switch112D and the fourth pressure-sensitive switch 112E are preferablybetween 30 and 50 mm. The distance between the first pressure-sensitiveswitch 112B and the fifth pressure-sensitive switch 112F in the fore andaft direction is preferably between 60 mm and 80 mm. These numericalranges include the boundary values.

The control unit 122 determines if the occupant is seated according tothe conductive state (ON, OFF) of the seat sensor 110. Further, thecontrol unit 122 determines if a seat belt is worn in each seatingregion 105. When the control unit 122 has determined that the occupantis seated in the seating region 105, and the seat belt is not worn, theoccupant is warned by sound or by turning on an alarm lamp.

The effect of the seat sensor 110 of the present embodiment is discussedin the following. The sheet material 111 includes the main part 111Aextending laterally, and the first to eighth branch part 111B to 111Jextending forward or rearward from the main part 111A. The first toeighth pressure-sensitive switch 112B to 112J are provided at the tipsof the first to eighth branch parts 111B to 111J, respectively.Therefore, each adjacent pair of pressure-sensitive switches 112B to112J are connected to each other via the two corresponding branch parts111B to 111J and the main part 111A. Therefore, when a load is appliedto a certain pressure-sensitive switch 112B-112J, the deformation of thebranch part 111B-111J on which the pressure-sensitive switch 112B-112Jis located is not likely to be transmitted to the branch part 111B to111J on which the adjacent pressure-sensitive switch 112B-112J islocated. In particular, when the pressure-sensitive switches 112 arelinearly arranged laterally as is the case with the first to fourthpressure-sensitive switches 112B to 112E or the fifth to eighthpressure-sensitive switches 112F to 112J, erroneous detection of thepressure-sensitive switches 112B to 112J due to the deformation of thesheet material 111 can be minimized.

Since the occupant's hip point HP is located on the first imaginarystraight line L1, the first to fourth pressure-sensitive switches 112Bto 112E are thus positioned at parts where the occupant's load is mostlikely to be applied.

When at least one of the first pressure-sensitive switch 112B and thesecond pressure-sensitive switch 112C is turned on and at least one ofthe third pressure-sensitive switch 112D and the fourthpressure-sensitive switch 112E is turned on, the detection circuit 115is turned on so that the seating sensor 110 detects the seating of aseat occupant. Therefore, even when the occupant's stature/build variesor the occupant's seating position is shifted to the left or to theright, the seat sensor 110 can reliably detect the occupant. Forexample, when the occupant is person of a large stature/build, all ofthe first to fourth pressure-sensitive switches 112B to 112E are turnedon so that the detection circuit 115 is turned on. When the occupant issmall like a child, the second and third pressure-sensitive switches112C and 112D are turned on so that the detection circuit 115 is turnedon. When the occupant is seated with a shift to the left, at least oneof the first and second pressure-sensitive switches 112B and 112C, andthe third pressure-sensitive switch 112D are turned on so that thedetection circuit 115 is turned on. When the occupant is seated with ashift to the right, at least one of the third and fourthpressure-sensitive switches 112D and 112E and the secondpressure-sensitive switch 112C are turned on so that the detectioncircuit 115 is turned on.

Further, since the front switch row including the fifth to eighthpressure-sensitive switches 112F to 112J are provided in front of therear switch row including the first to fourth pressure-sensitiveswitches 112B to 112E, even when the occupant is seated with a forwardshift, the seat sensor 110 can reliably detect the occupant by the frontswitch row.

Since the first pressure-sensitive switch 112B is configured to beturned on under a load greater than the second pressure-sensitive switch112C, and the fourth pressure-sensitive switch 112E is configured to beturned on under a load greater than the third pressure-sensitive switch112D, the sensor 110 is prevented from erroneously detecting an objectother than a person as an occupant. When the occupant is seated with alateral shift, the load applied to the pressure-sensitive switch 112located on the side of the shifted direction (the firstpressure-sensitive switch 112B when the occupant is seated with aleftward shift) becomes larger than the load applied to thepressure-sensitive switch 112C, 112D located on the side away from theshifted direction. When the occupant has a large stature/build, the loadapplied to the laterally outer pressure-sensitive switches 112B and 112Eincreases. When the stature/build of the occupant is small, the loadapplied to the laterally inner pressure-sensitive switches 112C and 112Dincreases. Therefore, a seat occupant can be detected in an appropriatemanner if the load under which the first and fourth pressure-sensitiveswitches 112B and 112E that are located on the laterally outer sides areturned on is greater than the load under which the second and thirdpressure-sensitive switches 112C and 112D that are located on thelaterally inner sides are turned on. By making the load under which thefirst and fourth pressure-sensitive switches 112B and 112E that locatedon the laterally outer sides are turned on to be greater than the loadunder which the second and third pressure-sensitive switches 112C and112D located on the laterally inner sides are turned on, the first andfourth pressure-sensitive switches 112B and 112E are prevented fromerroneously turning on under a load of an object lighter than a person.The same applies to the fifth to eighth pressure-sensitive switches 112Fto 112J located on the front side.

Fourth Embodiment

As shown in FIG. 11, a pair of vehicle seats 201 according to a fourthembodiment of the present invention are arranged in the vehicle widthdirection or laterally one next to the other on a floor 203 that definesa bottom portion of a cabin 202 of an automobile. The two vehicle seats201 are generally symmetrical to each other. The vehicle seats 201 formthe rear seats of the second or any subsequent row in the vehicle. Eachvehicle seat 201 includes a seat cushion 204 that supports the buttocksof a seated person, a seat back 205 provided at the rear end of the seatcushion 204 to function as a backrest, and a headrest 206 provided in anupper part of the seat back 205.

The seat cushions 204 has a substantially rectangular parallelepipedshape having a surface that faces substantially vertically. The uppersurface of the seat cushion 204 forms a seating surface 207 for a singleoccupant. The seating surface 207 is recessed downward in a laterallycentral part thereof, and is slightly inclined downward in the fore andaft direction toward the rear end thereof. Thus, the seating surface 207has a shape corresponding to the buttocks and thighs of a seat occupant.When a occupant is seated, the buttocks and thighs of the occupant arepositioned on the seating surface 207.

The seat back 205 extends vertically and has a substantially rectangularparallelepiped shape having a surface that faces substantially in thefore and aft direction. The front surface of the seat back 205 forms asupport surface 208 for supporting the occupant's back. The supportsurface 208 is recessed rearward substantially at a laterally centralpart thereof, and is inclined slightly rearward toward the upper endthereof. Thus, the support surface 208 has a shape corresponding to theback of the occupant, and the back of the occupant is supported by thesupport surface 208.

The lower end of the seat back 205 is pivotally supported by the rearend of the seat cushion 204 via a per se known reclining mechanism. Inother words, the seat back 205 is connected to the rear end of the seatcushion 204 at the lower end so as to be pivotable forward and backward.

As shown in FIG. 12, the seat cushion 204 includes a seat cushion frame(not shown) serving as a structural framework, a pad member 211supported by the seat cushion frame, and a skin material 212 placed onthe front surface of the pad member 211 to define the outer profile ofthe seat cushion 204.

As shown in FIG. 11, the upper surface of the pad member 211 of the seatcushion 204 includes an intermediate portion 213 which is inclineddownward toward the rear end thereof in a laterally middle part thereof,and a pair of bulging portions 214 bulging upward on either lateral sideof the intermediate portion 213. As shown in FIG. 13, the upper surfaceof the pad member 211 of the seat cushion 204 is further provided with afirst lateral listing groove 215 extending laterally at a substantiallymiddle part with respect to the fore and aft direction, and a pair offirst longitudinal listing grooves 216 extending from the front edge andthe rear edge of the seat cushion 204. Each first longitudinal listinggroove 216 is formed substantially along the boundary between theintermediate portion 213 and the corresponding bulging portion 214. Thefirst lateral listing groove 215 is connected to the first longitudinallisting grooves 216 at the respective ends thereof.

The first lateral listing groove 215 and the first longitudinal listinggrooves 216 each consist of a downwardly recessed groove formed on theupper surface of the pad member 211 (refer to FIG. 12 for the firstlateral listing groove 215). The skin material 212 covering the padmember 211 is provided with a plurality of hook members 217 at positionscorresponding to the first lateral listing groove 215 and the firstlongitudinal listing grooves 216. Each hook member 217 is inserted intothe first lateral listing groove 215 or the first longitudinal listinggroove 216. A fixing member 218 is provided inside each of the firstlateral listing groove 215 and the first longitudinal listing grooves216. The hook members 217 are hooked onto the corresponding fixingmembers 218 so that the skin material 212 is pulled into in the firstlateral listing groove 215 and the first longitudinal listing grooves216 via corresponding listing strips. Therefore, the first laterallisting groove 215 and the first longitudinal listing grooves 216 can beconsidered as grooves provided in the seat cushion 204 for pulling theskin material 212 into the seat cushion 204.

As shown in FIG. 12, a pressure-sensitive sensor unit 219 for detectinga load applied to the seating surface 207 is provided between the frontsurface of the pad member 211 of the seat cushion 204 and the backsurface of the skin material 212 of the seat cushion 204. Thepressure-sensitive sensor unit 219 consists of a flexible sheet-likemember incorporated with a plurality of pressure-sensitive switches 220(see FIG. 11), and thus forms a so-called membrane switch. Eachpressure-sensitive switch 220 is provided with an electrode placed alongthe surface of the pressure-sensitive sensor unit 219. Eachpressure-sensitive switch is turned on (or conducts) when a load equalto or greater than a predetermined value is applied to the electrode bypressing the surface of the pressure-sensitive sensor unit 219.Therefore, the pressure-sensitive switches 220 function as pressuresensors that detect the pressure applied to the electrodes. The pressuresensor unit 219 includes a first subunit 221 and a second subunit 222.Each of the first subunit 221 and the second subunit 222 consists of asheet-like member, and is incorporated with a plurality ofpressure-sensitive switches 220. As shown in FIG. 12, the first subunit221 and the second subunit 222 are arranged so as to extend in thelateral direction along the surface of the pad member 211. The back sideof the first subunit 221 and the back side of the second subunit 222 arein contact with the front surface of the pad member 211 of the seatcushion 204. The first subunit 221 and the second subunit 222 areconnected to each other by wiring 223.

As shown in FIG. 13, the first subunit 221 is positioned in front of thefirst lateral listing groove 215 and between the left and right firstlongitudinal listing grooves 216. The second subunit 222 is locatedbehind the first lateral listing groove 215 and between the left andright first longitudinal listing grooves 216. Thus, thepressure-sensitive switches 220 are provided both ahead of and behindthe first lateral listing groove 215.

In the present embodiment, the first subunit 221 and the second subunit222 are each provided with two pairs of pressure-sensitive switches 220,each pair consisting of two pressure-sensitive switches 220 positionedlaterally next to each other. The pressure-sensitive switch pairs arepositioned at the left and right ends of the first subunit 221,respectively, and the pressure-sensitive switch pairs are positioned atthe left and right ends of the second subunit 222, respectively. Morespecifically, one of the pressure-sensitive switch pairs (the first leftpressure-sensitive switch pair 225L) are provided at the left end of thefirst subunit 221, and the other pressure-sensitive switch pair (thefirst right pressure-sensitive switch pair 225R) are provided at theright end of the first subunit 221. Similarly, one of thepressure-sensitive switch pairs (the second left pressure-sensitiveswitch pair 226L) are provided at the left end of the second subunit222, and the other pressure-sensitive switch pair (the second rightpressure-sensitive switch pair 226R) are provided at the right end ofthe second subunit 222. Further, the first left pressure-sensitiveswitch pair 225L and the first right pressure-sensitive switch pair 225Rlaterally align with each other (coincide with each other with respectto the fore and aft positioning), and the second left pressure-sensitiveswitch pair 226L the second right pressure-sensitive switch pair 226Rlaterally align with each other (coincide with each other with respectto the fore and aft positioning).

FIG. 14 shows a circuit diagram of the pressure-sensitive sensor unit219. As shown in FIG. 14, the pressure-sensitive switches 220 includedin each pressure-sensitive switch pair 224L, 224R, 225L and 225R areconnected in parallel to each other (two-dot chain lines in FIG. 14). Inother words, each pressure-sensitive switch pair 224L, 224R, 225L and225R is turned on when either one of the correspondingpressure-sensitive switches 220 is turned on. Further, when the firstleft pressure-sensitive switch pair 225L or the second leftpressure-sensitive switch pair 226L is ON and the first rightpressure-sensitive switch pair 225R or the second rightpressure-sensitive switch pair 226R is turned ON, the sensor unit 219turns ON and becomes conductive.

As shown in FIG. 12, the seat back 205 is provided with a seat backframe (not shown) serving as a structural framework, a pad member 231supported by the seat back frame, and a skin material 232 placed on thesurface of the pad member 231 to define the outer profile of the seatback 205.

As shown in FIG. 11, the front surface of the pad member 231 of the seatback 205 includes an intermediate portion 233 that is locatedsubstantially laterally central part thereof and inclined upward towardthe rear end thereof, and a pair of bulging portions 234 bulging forwardalong either side of the intermediate portion 233. Further, the frontsurface of the pad member 231 is provided with a second lateral listinggroove 235 extending laterally at a substantially central portion in thevertical direction, and a pair of second longitudinal listing grooves236 extending from the upper edge to the lower edge of the pad member231. The second lateral listing groove 235 extends substantially betweenthe boundaries between the intermediate portion 233 and the bulgingportions 234, and the second lateral listing groove 235 is connected tothe second longitudinal listing grooves 236 at the two ends thereof,respectively.

The second lateral listing groove 235 and the second longitudinallisting grooves 236 each consist of a rearwardly recessed groove formedon the front surface of the pad member 231 of the seatback 205. Thesecond lateral listing groove 235 and the second longitudinal listinggrooves 236 are provided for pulling the skin material 232 of the seatback 205 into the cushion member, similarly to the first lateral listinggroove 215 and the first longitudinal listing grooves 216 mentionedearlier.

As shown in FIG. 19, a capacitance sensor 240 is positioned between thefront surface of the pad member 231 of the seat back 205 and the backsurface of the skin material 232. The capacitance sensor 240 is in theform of a flexible film. The capacitance sensor 240 is a non-contacttype proximity sensor that is turned on by an approaching object. Morespecifically, the capacitance sensor 240 is turned ON when an objecthaving a large relative dielectric constant is located within apredetermined distance (detection distance) from the surface thereof.The object having a large relative permittivity as discussed here is anobject having a relative permittivity of 10 or more, more preferably 30or more, and includes water, a human body and the like. The detectiondistance is 10 cm or less, and more preferably 30 cm or less.

As shown in FIG. 12, the capacitance sensor 240 is provided along thefront surface of the pad member 231 of the seat back 205. As shown inFIG. 11, the capacitance sensor 240 is positioned between the left andright second longitudinal listing grooves 236. The capacitance sensor240 is positioned below the second lateral listing groove 235 and at alocation corresponding to the occupant's hip region H (lumbar region),or in other words, behind the occupant's hip region H (see FIG. 12).More precisely, the hip region H means the back part of the occupantlocated behind the lumbar vertebra of the occupant, and the location ofthe hip region is preferably determined by using a three-dimensionalsitting human model for measuring the size of the vehicle interiordimensions as specified in MS D4607.

As shown in FIGS. 11 and 12, the vehicle seat 201 is provided with adetermination unit 246 for determining the seating of an occupant. Thedetermination unit 246 consists of a computer including a centralprocessing unit (CPU) and a storage device such as memory, and includesan input unit to receive an external signal and an output unit toforward a signal to the outside. The determination unit 246 is connectedto the pressure-sensitive sensor unit 219 and the capacitance sensor 240at the input unit thereof. In the present embodiment, the determinationunit 246 is attached to the lower surface of the seat cushion 204 of thevehicle seat 201. The determination unit 246 executes a determinationprocess to determine if the occupant is seated according to the signalfrom the pressure-sensitive sensor unit 219 received at the input unit(ON/OFF of the pressure-sensitive sensor unit 219), and the signal fromthe capacitance sensor 240 received at the input unit (ON/OFF of thecapacitance sensor 240). The details of the determination process aredescribed in the following with reference to the flowchart shown in FIG.15.

As shown in FIG. 15, in the first step ST1, the determination unit 246determines if the pressure-sensitive sensor unit 219 is ON or OFF. Whenthe pressure-sensitive sensor unit 219 is ON, step ST2 is executed, andwhen the pressure-sensitive sensor unit 219 is OFF, the determinationprocess ends.

The determination unit 246 determines if the capacitance sensor 240 isON or OFF in step ST2. The determination unit 246 executes step ST3 whenthe capacitance sensor 240 is ON, and ends the determination processwhen the capacitance sensor 240 is OFF.

In step ST3, the determination unit 246 outputs a signal indicating thatan occupant is seated from the output unit, and ends the determinationprocess.

The output unit of the determination unit 246 may be connected to acontrol unit 248 (ECU) mounted on the vehicle body. The control unit 248(ECU) may be, for example, a computer that controls the motion of thevehicle body. When the vehicle is driven, the control unit 248 instructsthe determination unit 246 to execute the determination process,receives the signal output from the determination unit 246, anddetermines if a seat belt is worn by the seated occupant as required.When the control unit 248 determines that the seat belt is not worn bythe seated occupant as required, the control unit 248 may issue awarning to the occupant.

The effect of the vehicle seat 201 is discussed in the following. Thedetermination unit 246 outputs a signal corresponding to the fact thatthe occupant is seated when the pressure-sensitive sensor unit 219 is ONand the capacitance sensor 240 is ON. In other words, the determinationunit 246 determines the seating of the occupant based on the signal (ON,OFF) from the pressure-sensitive switch 220 included in thepressure-sensitive sensor unit 219 and the signal (ON, OFF) from thecapacitance sensor 240.

Suppose that the occupant is seated on the vehicle seat 201, and a loadis applied to the part of the seating surface 207 indicated by the shadein FIG. 16(A). As a result, the second left pressure-sensitive switchpair 226L and the second right pressure-sensitive switch pair 226R areturned ON so that the pressure-sensitive sensor unit 219 is turned ON.As shown in FIG. 16(B), when the occupant is seated more forward than inthe case of FIG. 16(A), the first pair of left pressure-sensitiveswitches 225L and the first pair of right pressure-sensitive switches225R are turned on. As a result, the pressure-sensitive sensor unit 219turns ON. As shown in FIG. 16 (C), even when the occupant is seated moreto the right than in the case of FIG. 16 (A), the righthand-sidepressure-sensitive switch 220 of the second left pressure-sensitiveswitch pair 226L and the righthand-side pressure-sensitive switch 220 ofthe second right pressure-sensitive switch pair 226R are turned ON. As aresult, the pressure-sensitive sensor unit 219 turns ON. As discussedabove, by using the pressure-sensitive sensor unit 219 in this manner,the pressure-sensitive sensor unit 219 is turned on even when theoccupant is displaced either in the forward or in the lateraldirections.

However, as shown in FIG. 16 (D), suppose that a sack of rice (weighingabout 30 kg) is placed on the seating surface 207, and a load is appliedto the portion as indicated by the shade. This causes the second leftpressure-sensitive switch pair 226L and the second rightpressure-sensitive switch pair 226R to be turned on. In this case, ifthe determination unit 246 makes the determination based only on thesignal from the pressure-sensitive sensor unit 219, an erroneous signalwill be output.

However, in the present embodiment, the capacitance sensor 240 is turnedon when an object having a high relative permittivity is located withina detection distance from the surface thereof. More specifically, thecapacitance sensor 240 is turned ON when an object having a highrelative dielectric constant, such as water or a human body, is locatedwithin a detection distance from a portion of the support surface 208corresponding to the back of the hip region of the human body.Therefore, when the occupant (whose relative permittivity is about 40)is seated on the seating surface 207, or when the occupant is seated asshown in any of FIGS. 15(A) to 15(C), the capacitance sensor 240 isturned ON. On the other hand, when a sack of rice (having a relativedielectric constant of about 4) is placed on the seating surface 207, orin the case of FIG. 15(D), the capacitance sensor 240 is turned OFF. Asdescribed above, since the determination unit 246 determines if theoccupant is seated or not according to the signal from thepressure-sensitive switch 220 and the signal from the capacitance sensor240, the determination unit 246 is able to distinguish an object havinga large weight and a low relative permittivity, such as a sack of rice.As described above, by configuring the determination unit 246 so as toperform the determination process based on the signal from thepressure-sensitive switch 220 and the signal from the capacitance sensor240, it is possible to distinguish between the case where the occupantis seated on the vehicle seat 201 and the case where an article otherthan a human is placed on the seating surface 207 in a reliable manner.

In the present embodiment, as shown in FIG. 11, the pressure-sensitivesensor unit 219 is provided on the seat cushion 204, and the capacitancesensor 240 is provided on the seat back 205. Accordingly, as compared toa case where both the pressure-sensitive sensor unit 219 and thecapacitance sensor 240 are provided on the seat cushion 204, wiring forthese sensor units can be simplified, and the assembly work isfacilitated. Further, since the pressure-sensitive sensor unit 219 andthe capacitance sensor 240 are provided in separate members, they do notoverlap with each other. Thereby, these two sensor units can be bothpositioned close to the seating surface 207 with which the occupant'sbody comes into contact at the time of seating so that the sensitivitycan be improved for both the sensor units.

If the electrodes of the pressure-sensitive switches 220 of thepressure-sensitive sensor unit 219 are positioned near the capacitancesensor 240, the capacitance may not be measured accurately, and thesensitivity of the capacitance sensor 240 may be impaired. Also, whenthe capacitance sensor 240 is located on the surface of the pressuresensor unit 219, the weight of the capacitance sensor 240 may cause thepressure sensor unit 219 to be erroneously turned on. In the presentembodiment, since the pressure-sensitive sensor unit 219 and thecapacitance sensor 240 are provided in the separate members, they do notinterfere with each other so that the pressure-sensitive sensor unit 219and the capacitance sensor 240 are allowed to operate withoutinterfering with each other.

As shown in FIG. 12, the capacitance sensor 240 is positioned so as tocorrespond to the hip region H of the occupant, more specifically,behind the lumbar spine of the occupant. When the occupant is seated,the hip region H of the occupant is likely to contact or approach thesupport surface 208 of the seat back 205. By providing the capacitancesensor 240 at a position corresponding to the hip region H of the seatedoccupant, the capacitance sensor 240 can be brought closer to the bodyof the seated occupant. Thereby, the body of the seated occupant can bemore reliably detected by the capacitance sensor 240.

As shown in FIG. 13, the first subunit 221 and the second subunit 222are respectively positioned ahead of and behind the first laterallisting groove 215 and between the left and right first longitudinallisting grooves 216. By thus positioning the pressure-sensitive sensorunit 219 so as to avoid the first lateral listing groove 215 and thefirst longitudinal listing grooves 216, the pressure-sensitive sensorunit 219 can be arranged without any difficulty, and the deformation anddisplacement of the sensor unit 219 can be avoided. Further, byarranging the first subunit 221 and the second subunit 222 separatelyahead of and behind the first lateral listing groove 215, the pressureapplied to the seating surface 207 of the seat cushion 204 can bedetected over a wider range. Accordingly, even when the occupant isseated on the front portion of the seating surface 207 or seated with alateral shift, the seating of the occupant can be more reliablydetected.

As shown in FIG. 11, the capacitance sensor 240 is positioned betweenthe left and right second longitudinal listing grooves 236. By thusarranging the capacitance sensor 240 so as to avoid the listing grooves,assembling of the capacitance sensor 240 can be facilitated, and thedeformation and displacement of the capacitance sensor 240 can beavoided,

Fifth Embodiment

The vehicle seat 251 according to a fifth embodiment of the presentinvention differs from that of the fourth embodiment in the number andarrangement of the capacitance sensors 240, the arrangement of thepressure-sensitive sensor units 219, and the contents of thedetermination process, but is otherwise similar to that of the fourthembodiment. Therefore, the parts similar those of the previousembodiment are omitted from the following description.

FIG. 17 is a top view of the vehicle seats 251 with the skin material212 removed from the left vehicle seat 251. As shown in FIG. 17, eachvehicle seat 251 of the fifth embodiment is provided with twocapacitance sensors 253 and 254. The two capacitance sensors 253, 254are both arranged on the seat cushion 204. More specifically, the seatcushion 204 is provided with the pressure-sensitive sensor unit 219 andthe two capacitance sensors 240. The two capacitance sensors 240 areboth positioned between the front surface of the pad member 211 formingthe seat cushion 204 and the back surface of the skin material 212.

One of the two capacitance sensors 240 or the capacitance sensor 253(first capacitance sensor 253) is positioned in front of the firstlateral listing groove 215, and between the longitudinal listing grooves216. The other capacitance sensor 254 (the second capacitance sensor254) is positioned behind the first lateral listing groove 215 andbetween the first longitudinal listing grooves 216. Thus, twocapacitance sensors 253 and 254 are arranged ahead of and behind thefirst lateral listing groove 215 extending laterally. The firstcapacitance sensor 253 and the second capacitance sensor 254 are eachformed in a sheet form, and has a substantially rectangular shapeelongated in the lateral direction. The back surfaces of the firstcapacitance sensor 253 and the second capacitance sensor 254 are insurface contact with the upper surface of the pad member 211 forming theseat cushion 204.

The first subunit 221 of the pressure-sensitive sensor unit 219 isarranged so as to at least partly overlap with the first capacitancesensor 253 in top view. In the present embodiment, the first subunit 221is positioned on top of the first capacitance sensor 253 such that thefirst subunit 221 is located inside the outer peripheral edge of thefirst capacitance sensor 253 when viewed from above. The back surface ofthe first subunit 221 is arranged so as to be in surface contact withthe first capacitance sensor 253.

The second subunit 222 of the pressure-sensitive sensor unit 219 isarranged so as to at least partly overlap with the second capacitancesensor 254 in top view. In the present embodiment, the second subunit222 is positioned on top of the second capacitance sensor 254, and thesecond subunit 222 is located inside the outer peripheral edge of thesecond capacitance sensor 254 when viewed from above. The back surfaceof the second subunit 222 is arranged so as to be in surface contactwith the second capacitance sensor 254.

The determination unit 246 determines if an occupant is seated from theON/OFF state of the pressure-sensitive sensor unit 219 and the ON/OFFstates of the two capacitance sensors 240 received from the input unit.The determination process executed by the determination unit 246 for thevehicle seat 251 according to the fifth embodiment is different from thefourth embodiment only in step ST2 so that the description of the otherparts of the determination process is omitted from the followingdescription.

In step ST2, the determination unit 246 determines if one of the firstcapacitance sensor 253 and the second capacitance sensor 254 is ON. Ifat least one of these two capacitance sensors is ON, step ST3 isexecuted. When both the first capacitance sensor 253 and the secondcapacitance sensor 254 are OFF, the determination process ends.

The effect of the vehicle seat 251 configured as described above isdiscussed in the following. The two capacitance sensors 240 are bothprovided so as to be close to the seating surface 207 of the seatcushion 204 on which the occupant sits. Since the seating surface 207 isa region where the seated occupant is highly likely to be in contactwith, the two capacitance sensors 240 are likely to be brought closer tothe seated occupant. This allows the capacitance sensors 240 to moreaccurately detect the occupant's seating.

Further, the first subunit 221 and the first capacitance sensor 253 arearranged so as to overlap each other when viewed from above, and thesecond subunit 222 and the second capacitance sensor 254 similarlyoverlap with each other. Therefore, the surface area of the pad member211 of the seat cushion 204 where the pressure-sensitive sensor unit 219and the capacitance sensor 240 are arranged can be reduced. By arrangingthe pressure-sensitive sensor unit 219 and the capacitance sensor 240 inthis manner, any discomfort to the seat occupant can be minimized.

In the present embodiment, further, the first subunit 221 is positionedinside the outer periphery of the first capacitance sensor 253, and thesecond subunit 222 is positioned inside the outer periphery of thesecond capacitance sensor 254. Owing to this arrangement, the area overwhich the pressure-sensitive sensor unit 219 and the capacitance sensor240 overlap with each other can be further increased. Accordingly, thesurface area of the pad member 211 of the seat cushion 204 where thepressure-sensitive sensor unit 219 and the capacitance sensor 240 arearranged can be minimized so that the discomfort to the seat occupantcan be further reduced.

The first capacitance sensor 253 and the second capacitance sensor 254are positioned ahead of and behind the first lateral listing groove 215,respectively, and between the left and right first longitudinal listinggrooves 216. Accordingly, the first capacitance sensor 253 and thesecond capacitance sensor 254 can be arranged so as to avoid the firstlateral listing groove 215 and the first longitudinal listing grooves216. As a result, the assembling of the pressure-sensitive sensor unit219 and the two capacitance sensors 253 and 254 can be facilitated, andthe deformation and displacement of the pressure-sensitive sensor unit219 and the two capacitance sensors 253 and 254 can be minimized. Sincethe first capacitance sensor 253 and the second capacitance sensor 254are arranged ahead of and behind the first lateral listing groove 215,respectively, the first capacitance sensor 253 is turned on when theoccupant is seated in a front part of the seating surface 207 while thesecond capacitance sensor 254 is turned on when the occupant is seatedin a rear part of the seating surface 207. As a result, the seating of aseat occupant over a wide range in the fore and aft direction can bedetected.

Sixth Embodiment

The vehicle seat 261 according to a sixth embodiment of the presentinvention is different from the vehicle seat 201 of the fifth embodimentin the shape of the first capacitance sensor 253 and the secondcapacitance sensor 254, but is otherwise similar to the vehicle seat ofthe fifth embodiment. Therefore, other parts of the vehicle seat 261 ofthe sixth embodiment are omitted from the following description.

FIG. 18 is a top view of two vehicle seats 261 of which the left vehicleseat 261 is shown with a part of the skin material 212 removedtherefrom. As shown in FIG. 18, the first capacitance sensor 253 and thesecond capacitance sensor 254 are each in a sheet form of asubstantially rectangular shape elongated in the lateral direction. Eachof the first capacitance sensor 253 and the second capacitance sensor254 is provided with an opening 263 and 264 passed verticallytherethrough. The openings 263 and 264 each have a substantiallyrectangular shape elongated in the lateral direction.

The first capacitance sensor 253 is located in front of the firstlateral listing groove 215 and between the first longitudinal listinggrooves 216 laterally spaced from each other. The second capacitancesensor 254 is positioned behind the first lateral listing groove 215 andbetween the first longitudinal listing grooves 216. Therefore, the twocapacitance sensors 253 and 254 having the openings 263 and 264 arerespectively arranged ahead of and behind the first lateral listinggroove 215 extending laterally. The back surfaces of the firstcapacitance sensor 253 and the second capacitance sensor 254 are insurface contact with the upper surface of the pad member 211 of the seatcushion 204.

The first subunit 221 is positioned inside the opening 263 of the firstcapacitance sensor 253. The back surface of the first subunit 221 is insurface contact with the pad member 211 of the seat cushion 204. In thepresent embodiment, the thickness of the first subunit 221 and thethickness of the first capacitance sensor 253 are substantially equal toeach other so that the upper surface of the first subunit 221 and theupper surface of the first capacitance sensor 253 are flush with eachother.

The second subunit 222 is positioned inside the opening 264 of thesecond capacitance sensor 254. The back surface of the second subunit222 is in surface contact with the pad member 211 of the seat cushion204. In the present embodiment, the thickness of the second subunit 222is substantially equal to the thickness of the second capacitance sensor254 so that the upper surface of the second subunit 222 and the uppersurface of the second capacitance sensor 254 are flush with each other.

The first capacitance sensor 253, the second capacitance sensor 254, thefirst subunit 221 and the second subunit 222 are all positioned betweenthe pad member 211 of the seat cushion 204 and the skin material 212.

The effect of the vehicle seat 261 configured as described above isdiscussed in the following. The first subunit 221 is positioned insidethe opening 263 of the first capacitance sensor 253 so that a step isless likely to be produced between the upper surface of the firstsubunit 221 and the upper surface of the first capacitance sensor 253.Similarly, the second subunit 222 is positioned inside the opening 264of the second capacitance sensor 254 so that a step is less likely to beproduced between the upper surface of the second subunit 222 and theupper surface of the second capacitance sensor 254. As a result, a stepis less likely to be produced on the seating surface 207 so that theseating comfort can be improved. In this embodiment, the upper surfaceof the first subunit 221 and the upper surface of the first capacitancesensor 253 are flush with each other, and the upper surface of thesecond subunit 222 and the upper surface of the second capacitancesensor 254 are also flush with each other so that the seating surface207 can be made of a highly even planar surface. Thereby, the sittingcomfort can be further improved.

The first capacitance sensor 253 and the second capacitance sensor 254are positioned between the left and right first longitudinal listinggrooves 216 and ahead of and behind the first lateral listing groove215, respectively. Therefore, the two capacitance sensors 253 and 254can be positioned so as to avoid the first lateral listing groove 215and the first longitudinal listing grooves 216. As a result, theassembling of the capacitance sensors 253 and 254 can be facilitated,and deformation and displacement of the pressure-sensitive sensor unit219 and the two capacitance sensors 253 and 254 can be minimized.Further, by arranging the two capacitance sensors 253 and 254 in frontof and behind the first lateral listing groove 215, respectively, theoccupant's seating can be detected over a wider range in the fore andaft direction.

Seventh Embodiment

The vehicle seat 271 according to a seventh embodiment of the presentinvention differs from the vehicle seat 201 of the fourth embodimentonly in the positioning of the capacitance sensor 240 and the structureand positioning of the pressure-sensitive sensor unit 219, but isotherwise similar to the vehicle seat 201 of the fourth embodiment.Therefore, the remaining parts of the vehicle seat 271 are omitted fromthe following description.

FIG. 19 is a top view of two vehicle seats 271 of which the left vehicleseat 271 is shown with a part of the skin material 212 removedtherefrom. As shown in FIG. 19, the capacitance sensor 240 is placedbetween the front surface of the pad member 211 of the seat cushion 204and the back surface of the skin material 212 of the seat cushion 204.The capacitance sensor 240 is positioned on the surface of the padmember 211 in front of the first lateral listing groove 215 and betweenthe left and right first longitudinal listing grooves 216. The backsurface of the capacitance sensor 240 is in surface contact with thefront surface of the pad member 211 of the seat cushion 204.

Unlike the preceding embodiment, the pressure-sensitive sensor unit 219does not include a second subunit 222, and instead consists solely ofthe first subunit 221. When the first left pressure-sensitive switchpair 225L is ON and the first right pressure-sensitive switch pair 225Ris ON, the pressure-sensitive sensor unit 219 is turned ON.

The pressure sensor unit 219 (the first subunit 221) is also providedbetween the front surface of the pad member 211 of the seat cushion 204and the back surface of the skin material 212 of the seat cushion 204.The pressure-sensitive sensor unit 219 is positioned behind the firstlateral listing groove 215 and between the left and right firstlongitudinal listing grooves 216. The back surface of thepressure-sensitive sensor unit 219 is in surface contact with the frontsurface of the pad member 211 of the seat cushion 204.

The effect of the vehicle seat 271 thus configured is discussed in thefollowing. Since both the pressure-sensitive sensor unit 219 and thecapacitance sensor 240 are positioned near the seating surface 207, theseating of an occupant can be detected with a higher sensitivity. Inaddition, since the pressure-sensitive sensor unit 219 and thecapacitance sensor 240 are positioned so as to avoid the first laterallisting groove 215 and the first longitudinal listing grooves 216, theassembling of these sensors to the seat cushion 204 is facilitated.Further, deformation and displacement of the pressure-sensitive sensorunit 219 and the capacitance sensor 240 when the occupant is seated canbe minimized. Further, by positioning the pressure-sensitive sensor unit219 behind the first lateral listing groove 215, the load of theoccupant can be made more likely to be transmitted to thepressure-sensitive sensor unit 219, as compared with the case where thepressure-sensitive sensor unit 219 is positioned in front of the firstlateral listing groove 215, so that the detection of the seating of anoccupant can be detected in a more reliable manner.

The present invention has been described in terms of specificembodiments, but is not limited by such embodiments, and can be modifiedin various ways without departing from the scope of the presentinvention. For example, in the first embodiment and the secondembodiment, the recess 45 may be provided in the floor portion 5 insteadof the back surface of the seat cushion pad 11. In other words, therecess 45 may be provided on one of the back surface of the seat cushionpad 11 and the floor portion 5. Similarly, the recess 45 may be providedon one of the back surface of the seat back pad 51 and the wall portion6.

In the first embodiment and the second embodiment, the open end of thewire harness passage 35 on the front surface side may also be providedinside the listing groove. The open end on the front surface side of thewire harness passage 35 may be provided in any one of the left and rightlongitudinal grooves and the front and rear lateral grooves.

In the third embodiment, the ninth branch part 111K may also extendrearward from the center of the main part 111A. In this case, theconnecting portion 114 may be provided at the rear end of the ninthbranch part 111K, and the connecting portion 114 may be positioned aheadof the first imaginary straight line L1. The ninth branch part 111K mayextend leftward from the left end of the main part 111A, and may extendrightward from the right end of the main part 111A. Each branch part111B to 111K may be curved or bent.

In the fifth embodiment, the pressure-sensitive sensor unit 219 and thecapacitance sensor 240 are provided separately, but thepressure-sensitive switch 220 and the capacitance sensor 240 may also beprovided on one sheet-like member. In the foregoing embodiments, thedetermination unit 246 is attached to the lower surface of the seatcushion 204, but the present invention is not limited to this mode. Forexample, the determination unit 246 may be placed on a predeterminedposition on the floor 203, or may be formed by software incorporated inthe control unit 248.

LIST OF REFERENCE NUMERALS

 1: seat of a first embodiment  2: seat cushion  3: seat back  4: bodypanel  5: floor portion  6: wall portion  11: seat cushion pad  12: skinmaterial  14: rigid part  15: soft part  20: listing groove  28: rearinclined portion  30: pressure receiving area  32: sensor  33: wireharness  35: wire harness passage  37: air passage  41: locking portion 45: recess  51: seat back pad  52: skin material  57: sensor  58: wireharness passage  59: wire harness  61: recess  70: seat of a secondembodiment  72: heater cloth 101: seat of a third embodiment 102: seatcushion 105: seating region 106: seat cushion pad 107: skin material110: seat sensor 111: sheet material 111A: the main part 111B to 111K:first to ninth branch parts 112B to 112J: first to eighthpressure-sensitive switches 113: wiring 114: connecting portion 116:first circuit 117: second circuit 118: third circuit 119: fourth circuit122: control unit 201: vehicle seat of a fourth embodiment 204: seatcushion 205: seat back 206: headrest 215: first lateral listing groove220: pressure-sensitive switch (pressure sensor) 236: secondlongitudinal listing groove 240: capacitance sensor 246: determinationunit 251: vehicle seat of a fifth embodiment 253: first capacitancesensor 254: second capacitance sensor 261: vehicle seat of a sixthembodiment 263, 264: opening 271: vehicle seat of a seventh embodimentHP: hip point L1: first imaginary straight line L2: second imaginarystraight line H: hip

1. A vehicle seat, comprising: a panel; a pad supported by the panel; askin material covering a front surface of the pad; and a sensor providedbetween the front surface of the pad and the skin material for acquiringinformation on a seat occupant, wherein the pad is provided with athrough hole passed from the front surface of the pad to a back surfaceof the pad, and a recess formed in the back surface of the pad andconnected to the through hole, the sensor being connected to a wireharness extending in the through hole and the recess.
 2. The vehicleseat according to claim 1, wherein the recess extends from the throughhole to an edge of the back surface of the pad.
 3. The vehicle seataccording to claim 1, wherein the surface of the panel faces vertically,the pad is placed on an upper surface of the panel so as to be rotatablearound a center located in a rear end portion thereof, and the recessextends rearward from the through hole.
 4. The vehicle seat according toclaim 1, wherein the surface of the panel faces in a fore and aftdirection, the pad is positioned on a front surface of the panel so asto be rotatable around a center located in a lower end portion thereof,and the recess extends downward from the through hole.
 5. The vehicleseat according to claim 1, wherein the pad includes a plurality ofmembers made of different materials, and the through hole is formed inone of the members.
 6. The vehicle seat according to claim 1, wherein anair passage extending from the back surface to the front surface isformed in the pad, and the through hole is formed so as to avoid the airpassage.
 7. The vehicle seat according to claim 1, wherein a lockingportion for fixing a child seat is formed on the surface of the pad, andthe through hole is formed so as to avoid the locking portion.
 8. Thevehicle seat according to claim 1, wherein a heater cloth having aheater wire is provided on the front surface of the pad, and the throughhole is positioned so as to avoid the heater cloth.
 9. The vehicle seataccording to claim 1, wherein one end of the through hole is provided ata position avoiding a pressure receiving area defined as an area on thesurface of the pad to which a load of a seat occupant is directlyapplied.
 10. The vehicle seat according to claim 9, wherein the surfaceof the panel faces vertically, the pad is positioned on an upper surfaceof the panel, and the through hole is provided behind the pressurereceiving area.